1. Field of the Invention
This invention relates to a multistage coal hydrogenation process and more particularly to special types of slurry oils for liquid phase coal hydrogenation.
2. Description of the prior Art
Presently, all coal hydrogenation processes use process derived oils for slurrying the coal feed in recognition of the principle that slurry oils must be chemically identical to coal oils. For example, see W. Kronig:Die Katalytische Druckhydrierung von Kohlen, Teeren und Mineralolen, Berlin/Gottingen/Heidelberg, 1950, page 76. However, there is some indication that non-process derived oils could be used as feedstocks for coal hydrogenation process, for example, as starting oils. See W. Kronig, id at 42.
It would, indeed be desirable to be able to use non-process derived oils for coal slurrying. A coal hydrogenation process using such oils would be very cost effective due to the avoidance of expensive process derived oil use. Unfortunately, to date, such expensive process derived oils have been used almost exclusively for slurrying the coal feed.
Thus, a need clearly continues to exist for a less expensive, but equally effective, alternative slurrying oil for coal hydrogenation processes.